It's not the first time something like this has happened. Pretty ridiculous either way. That's a violation of freedom of speech. But of course they get away with it because it's a private website and they can dictate terms. Boycott that site. Don't visit it again & engage with websites that provide value to the world. That's my opinion.
You are right, it is their site to do with as they please. I was just testing it out, in any case, but nonetheless, I was quite shocked since I never really believed all the stories going around about censorship. This makes me realize the people making those claims are perhaps not the nutters I thought they were...